剩余污泥与厌氧消化污泥的脱水性能对比

为了实现污水厂剩余污泥的资源化,污泥厌氧消化工艺的应用愈加普遍,厌氧消化过程是否会对剩余污泥的脱水性能产生影响是值得研究的问题。为此,利用加药污泥真空抽滤试验考察了污泥的脱水性能,结果表明,中温厌氧消化污泥(MADS)的比阻和过滤时间(TTF50)均大于剩余污泥(EAS)以及含水率接近厌氧消化污泥的浓缩后剩余污泥(TEAS),剩余污泥经浓缩后脱水速率有一定的降低,而厌氧消化过程会使剩余污泥的脱水速率大幅度降低。激光衍射粒度分析仪的测定结果显示,EAS及MADS的平均粒径分别为70.44、42.00μm,比表面积分别为2 122、3 743 cm2/m L;由紫外光谱和傅里叶变换红外光谱对胞外聚合物(EPS)的分析表明,厌氧消化后污泥液相中的核酸量大幅增加,细胞壁被破坏,蛋白质和多聚糖等大分子物质被降解为小分子物质。由污泥理化特性的检测结果可以推断,厌氧消化污泥的脱水速率低于剩余污泥,但若加大脱水压差或延长脱水时间,厌氧消化污泥的泥饼含水率会更低。     

城市污水处理厂污泥的好氧处理研究

为了实现污泥的稳定化、减量化和无害化,对城市污水处理厂的浓缩污泥和厌氧消化污泥进行了好氧处理试验研究.试验结果表明,污泥好氧处理使污泥中有机物质含量降低,臭味减小.厌氧污泥经好氧消化处理后,一方面使污泥得到稳定化和减量化;另一方面,可以把污泥中的致病菌杀死.污泥经好氧消化后沉降性能有明显提高,絮凝剂的加入使其脱水性能也得到一定的改善.     

高级厌氧消化污泥深度脱水调理技术优化研究

研究了高级厌氧消化处理对污泥脱水性能的影响以及不同调理条件下高级厌氧消化污泥的深度脱水效果,优选了适用于高级厌氧消化污泥的深度脱水调理技术。结果表明,经高级厌氧消化处理后污泥的有机物含量降低,颗粒粒径变小,脱水性能变差;对于高级厌氧消化污泥,采用石灰单独调理、石灰与铁盐复合调理均无法实现板框压滤深度脱水,而采用石灰与PAM复合调理、铁盐与PAM复合调理则可实现深度脱水,脱水泥饼含水率可降至60%以下。因此,已有深度脱水设施在处理高级厌氧消化污泥时,需要对调理方式进行调整。     

蚯蚓生物滤池处理剩余污泥的脱水性能研究

蚯蚓生物滤池基于蚯蚓与微生物的协同作用,可有效实现剩余污泥的减量化和稳定化,其中由于蚯蚓的摄食、咀嚼和消化等作用及蚓粪的团聚作用可有效改善污泥的脱水性能。在有机负荷为2.43 kg VSS/(m~3·d)的条件下,结合持泥量变化情况,比较了木珠、鲍尔环、瓷球三种不同填料的蚯蚓生物滤池处理剩余污泥的减量化和稳定化效果,并选取运行最稳定高效的木珠填料生物滤池进行脱水性能试验。以污泥比阻、毛细吸水时间、Zeta电位、污泥颗粒粒径、絮体结构、EPS为指标,考察了处理前后污泥脱水性能的变化。结果表明,经蚯蚓生物滤池处理后的污泥比阻和毛细吸水时间减少,Zeta电位升高,污泥颗粒粒径增大,絮体结构更为紧密,脱水性能大大改善。最后结合蚯蚓与微生物的相互作用关系,分析了蚯蚓生物滤池改善污泥脱水性能的机制。     

DO对硫杆菌污泥调理系统脱水效能的影响

针对现有污泥调理技术对污泥脱水性能改善效能低,难以达到现行污泥处置标准对含水率要求的问题,提出了剩余污泥氧化硫硫杆菌生物调理技术,考察了DO对剩余污泥硫杆菌生物调理系统深度脱水效能的影响.在DO为6 mg/L条件下,氧化硫硫杆菌生物调理系统调理污泥脱水后的含水率由75.5％降至63.6％;EPS中蛋白质、腐殖质、多糖分别减少为3.67、3.15、16.17mg/gVSS,污泥结合水含量从2.63 g/gDS降低至1.48 g/gDS;污泥Zeta电位从-14.9 mV降低至0.27 mV,污泥絮体颗粒平均粒径由20.19 μm增大到34.51 μm,硫杆菌生物调理系统对污泥脱水性能改善显著.     

溶菌酶预处理对剩余污泥脱水性能的影响

将溶菌酶应用于剩余污泥的预处理,考察了不同酶投加量对污泥脱水性能的影响,通过测定滤饼含水率、污泥比阻、污泥毛细吸水时间（CST）、Zeta电位及污泥上清液中的蛋白质和多糖含量,并采用显微镜和扫描电镜观测污泥絮体和颗粒结构的变化,同时结合三维荧光光谱分析,研究原污泥和酶处理后污泥的脱水性能差异。结果表明,适宜的溶菌酶投加量可显著改善剩余污泥的脱水性能,与原污泥相比,当酶投加量为15%时,真空抽滤后的含水率由91.4%降到63.6%,比阻降低了82%,CST降低了65%,Zeta电位从-14.8 mV上升到2.7 mV。溶菌酶对污泥结构的破坏是其改善污泥脱水性能的重要原因。     

添加碱渣对污泥厌氧消化的影响研究

将碱渣与城市污水处理厂的剩余污泥按不同的比例均匀混合后,进行厌氧消化试验,并根据消化液中SCOD、pH值及产气量等指标的变化,分析了碱渣对污泥厌氧消化性能的影响.结果表明:在碱渣添加量<8.25 g/L时,对污泥厌氧消化中的水解反应有较大的促进作用,溶出的有机物可生物降解性好;在试验的碱渣添加量范围内,厌氧消化液的pH值维持在7～8,显示碱渣对污泥消化产生的有机酸具有一定的缓冲作用;当碱渣添加量为3.30 g/L时,产气量和甲烷产量最大且厌氧消化反应速度最快,与未添加碱渣的相比则甲烷产量提高了约37.9%.碱渣中含有的碱性物质对污泥厌氧消化有较大的促进作用.     

ICSTD反应器对剩余污泥的浓缩消化研究

采用新型内循环污泥浓缩消化反应器(ICSTD)对污水处理厂剩余污泥进行浓缩消化处理,系统运行稳定后对反应器内污泥特性进行研究。结果表明:在温度为30~35℃时,污泥产气率最高为1.6 m3/m3泥;所产沼气的甲烷含量在54%~75%之间;反应器运行期间污泥比阻从513×1012m/kg降低到202×1012m/kg,污泥脱水性能逐渐变好;对污泥所含元素进行分析,发现反应器消化效果较好,具有一定的脱氮效能。反应器内污泥优势菌属为鬃毛甲烷菌。     

污泥龄对活性污泥絮体中磷形态与分布的影响

以污泥龄分别为4和20 d的两组SBR反应器为研究对象,利用SMT法测定活性污泥、细菌细胞和EPS中磷的形态与分布,探讨了污泥龄对活性污泥中磷形态和分布的影响。研究结果表明,高SRT污泥的TP含量约为低SRT污泥的1.56倍,这主要是由于前者较后者有更高的OP和AP含量。高SRT污泥中细菌细胞和EPS的TP含量均高于低SRT污泥中的,且高SRT污泥中EPS的OP含量远大于低SRT污泥中的。高SRT污泥的细菌细胞和EPS分别较低SRT污泥的细菌细胞和EPS有更大的厌氧释磷量和好氧吸磷量,前者厌氧释磷和好氧吸磷主要源自其OP含量的变化,后者则主要源自其IP含量的变化;在厌氧/好氧反应过程中,污泥中EPS的IP含量改变主要源自其NAIP含量的变化。     

白龙港污水处理厂污泥厌氧消化系统的设计和调试

白龙港污泥处理工程主要处理白龙港污水处理厂200×104 m3/d污水处理产生的污泥,采用浓缩、中温厌氧消化、污泥脱水和部分脱水污泥干化处理工艺,消化产生的沼气用于加热消化池污泥,多余的沼气作为能源干化脱水污泥。干化处理后冷凝水的余热回收辅助用于污泥消化系统供热。介绍了污泥厌氧消化系统的设计参数、工艺特点及调试情况,可供设计人员参考。     

Characterization of activated sludge exocellular polymers using several cation-associated extraction methods

Evaluation of prior research and preliminary investigations in our laboratory led to the development of an extraction strategy that can be used to target different cations in activated sludge floc and extract their associated extracellular polymeric substances (EPS). The methods we used were the cation exchange resin (CER) procedure, base extraction, and sulfide addition to extract EPS linked with divalent cations, Al, and Fe, respectively. A comparison of sludge cations before and after CER extraction revealed that most of Ca(2+) and Mg(2+) were removed while Fe and Al remained intact, suggesting that this method is highly selective for Ca(2+) and Mg(2+)-bound EPS. The correlation between sludge Fe and sulfide-extracted EPS was indicative of selectivity of this method for Fe-bound EPS. The base extraction was less specific than the other methods but it was the method releasing the largest amount of Al into the extract, indicating that the method extracted Al-bound EPS. Concomitantly, the composition of extracted EPS and the amino acid composition differed for the three methods, indicating that EPS associated with different metals were not the same. The change in EPS following anaerobic and aerobic digestion was also characterized by the three extraction methods. CER-extracted EPS were reduced after aerobic digestion while they changed little by anaerobic digestion. On the other hand, anaerobic digestion was associated with the decrease in sulfide-extracted EPS. These results suggest that different types of cation-EPS binding mechanisms exist in activated sludge and that each cation-associated EPS fraction imparts unique digestion characteristics to activated sludge.     

臭氧氧化/厌氧消化工艺处理CEPT污泥的研究

上海市白龙港污水处理厂采用化学一级强化处理工艺（CEPT），污泥产量大且稳定性差，直接脱水填埋很难满足有关环保要求，因此对其进行稳定化和减量化研究是污泥处理、处置工作的重中之重。为此，开展了臭氧氧化／厌氧消化工艺处理该类污泥的中试研究。结果表明，当臭氧投量为0．08kg／kgDS、臭氧氧化污泥量占进泥量的比例为67％、污泥投配率为5％时，臭氧氧化对厌氧消化的促进作用比较明显，对有机物的降解率较单纯厌氧消化的高约6．3％，产气量增加了近20．1％。此外，投加臭氧还能改善污泥的脱水性能，并减少了脱水时助凝剂的投量。     

螺旋压榨式脱水机对污泥脱水的试验研究

考察了螺旋压榨式脱水机对污泥的脱水性能.结果表明:对于含水率为97.9%的消化污泥,在絮凝剂投配率为0.51%、螺杆转速为0.25 r/min的条件下,脱水后泥饼含水率最低可达70.3%、固形物回收率为98.89%、污泥处理量为24.84 kg/h;对于含水率为99.7%的剩余污泥,在絮凝剂投配率为0.94%、螺杆转速为0.75 r/min的条件下,脱水后泥饼含水率为82.5%、固形物回收率为92.46%、污泥处理量为8.64 kg/h.螺旋压榨式脱水机对污泥的处理效果较带式脱水机有很大提高.     

Physico-chemical characteristics of full scale sewage sludges with implications to dewatering

An investigation was carried out for a variety of different sewage sludges in order to establish correlations between sludge composition, structure and dewatering properties. Results indicated that the fraction of extracellular polymeric substances (EPS) in sludges was the most important parameter with respect to sludge structure. With high EPS contents, sludges had a lower shear sensitivity and lower degree of dispersion. This in turn lead to better filterability in terms of low resistance to filtration (SRF). The floc stabilising role of EPS components was not consistent with DLVO-theory, as the zeta-potential increased with increased EPS content due to increased EPS charge content. This indicates that polymer entanglement is a key factor to stable floc structure. This does not rule out the possible change in dispersion due to changed electrostatic repulsion for a given EPS content. While EPS had a good effect on floc stability and filterability, the cake dry matter content decreased with large EPS contents. This could be due to an osmotic pressure related to the polymer charge quantity, or it could be caused by water entrapment in the floc structures. A high degree of sludge dispersion increased the cake dry matter content in filtration. This mechanism is, however, impractical due to high SRF and not important to conditioned sludge. In practice, dewatering also includes sludge expression. Taking this into account, osmosis related to EPS charges is likely to be increasingly important (increasing the negative effect of EPS content on cake dry matter).     

胞外聚合物的生成特性及其对污水生物处理的影响

微生物产生的胞外聚合物(EPS)是活性污泥生物絮体的主要组成部分,而且不同基质条件会对其产生不同的影响。在活性污泥中,EPS的存在对生物絮凝、沉降及脱水性能等具有重要的影响,在控制和改善污泥处理过程中起着举足轻重的作用;阐述了EPS对膜污染的贡献,及其对金属离子的络合作用。     

Performance improvement and decolourization in the high-solid thermophilic anaerobic digestion of thermally pretreated sewage sludge

This laboratory-scale study attempted performance improvement and decolourization in the high-solid thermophilic anaerobic digestion of thermally pretreated sewage sludge, as it tends to be disturbed by ammonia inhibition and colour generation. Sewage sludge was adjusted to 7%–8% total solids (TS), and pretreated at 150°C for 1 h. The digesters were operated at 55°C and 20 days hydraulic retention time. An addition of powdered activated carbon (approximately 2% of the feed TS) significantly contributed to the removal of propionate and reduced the colour in digested sludge by about 27%. Microbial analysis detected less abundance of bacterial Synergistia and archaeal Methanosarcina and implied more hydrogenotrophic methanogenesis with the activated carbon addition. Conditioning with ferric chloride for dewatering digested sludge mitigated the colour of dewatered liquor by about 67%. Therefore, these methods were demonstrated to be effective and partly overcome the above-mentioned problems.     

Influence of wastewater treatment on sludge production and processing

The challenge of stricter wastewater standards is resulting in configuration changes to wastewater treatment. As facilities upgrade, the type of sludge produced is changing, with growing quantities of secondary and chemical sludge at the expense of primary sludge. It is already understood that secondary sludge is harder to treat than its primary equivalent; therefore, increasing the quantity of this type of sludge will have detrimental impacts downstream. As legislation tightens further, extended aeration times may be required during processing to remove more nutrients. Work has shown that extended aeration further exacerbates the treatability of secondary sludge. This paper explains how tightening wastewater legislation fundamentally alters the nature of the sludge produced, and how these alterations impact further processing, especially with respect to sludge production and type; sludge energy content; performance of anaerobic digestion and dewatering, and potential for thermal energy recovery.     

Effect of disintegrated sludge recycling on membrane permeability in a membrane bioreactor combined with a turbulent jet flow ozone contactor

We have combined a turbulent jet flow ozone contactor (TJC) with a membrane bioreactor (MBR) to establish a zero-discharge system in terms of excess sludge in the MBR. The TJC-MBR system was compared with the conventional MBR (Control-MBR) with respect to i) the size and zeta potential of the sludge particles, ii) the loosely bound extra-cellular polymeric substances (EPSs) and tightly bound EPS of the microbial flocs, iii) the porosity and biovolume of the bio-cake accumulated on the membrane, and iv) the membrane permeability. The TJC system generated the ozonated sludge with a negligible amount of loosely bound EPS and a positive zeta potential. As a result, when such ozonated sludge was recycled, the average size of the sludge particles (e.g., microbial flocs) increased in the TJC-MBR. Consequently the bio-cake formed in the TJC-MBR had greater porosity than that in the Control-MBR, giving rise to higher membrane permeability in the TJC-MBR.     

Mechanisms of floc destruction during anaerobic and aerobic digestion and the effect on conditioning and dewatering of biosolids

Laboratory anaerobic and aerobic digestion studies were conducted using waste activated sludges from two municipal wastewater treatment plants in order to gain insight into the mechanisms of floc destruction that account for changes in sludge conditioning and dewatering properties when sludges undergo anaerobic and aerobic digestion. Batch digestion studies were conducted at 20 degrees C and the dewatering properties, solution biopolymer concentration and conditioning dose requirements measured. The data indicated that release of biopolymer from sludges occurred under both anaerobic and aerobic conditions but that the release was much greater under anaerobic conditions. In particular, the release of protein into solution was 4-5 times higher under anaerobic than under aerobic conditions. Both the dewatering rate, as characterized by the specific resistance to filtration and the amount of polymer conditioning chemicals required was found to depend directly on the amount of biopolymer (protein + polysaccharide) in solution. Little difference in dewatering properties and conditioning doses was seen between the two activated sludges from different plants. Differences in the cations released between anaerobic and aerobic digestion suggest that the digestion mechanisms differ for the two types of processes. Enzyme activity data showed that during aerobic digestion, polysaccharide degradation activity decreased to near zero and this was consistent with the accumulation of polysaccharides in aerobic digesters.